I have a USB drive that I assign the drive letter U: to. Recently whenever I insert it into my Win 7 desktop it doesn't assign it the letter U. It tries to assign it H. If H is unavailable then it doesn't get a letter assigned and I have to manually reassign it each time by going into Disk Management.

Surely something must be wrong. I know I used to be able to assign it U: and have it use it automatically whenever I used it with this system.

Yep I have that same issue, had it on WIndows 7 and i've had it a few times on windows 8. When I plug 2 drives in to sync them with syncback I always have to go into syncback and change driver letters before I run it. My main external backup drives are B: and it always seem like i'm going in and resigning B to the backup drive.

I have never really had any issues - sure now and then if a mapped network drive set to what the usb used before than have some problems.

But here this should helphttp://www.uwe-sieber.de/usbdlm_e.html
USBDLM is a Windows service that gives control over Windows' drive letter assignment for USB drives. Running as service makes it independent of the logged on user's privileges, so there is no need to give the users the privilege to change drive letters.

It automatically solves conflicts between USB drives and network or subst drives of the currently logged on user. Furthermore you can define new default letters for USB drives and much more.